Conventionally, ultrasonic diagnosing devices for diagnosing a state of a to-be-examined part based on reflection echoes caused by ultrasonic waves transmitted to a to-be-examined part in a percutaneous manner, so as to analyze a state of the to-be-examined part that is an examination target in a to-be-examined body, are known. As such an ultrasonic diagnosing device, for example, Patent Document 1 discloses an ultrasonic probe supporting mechanism which supports an ultrasonic probe for transmitting ultrasonic waves via an acoustic matching member (ultrasonic wave penetrating part) having a curved shape along a kneecap (to-be-examined body), in a manner that the ultrasonic probe is movable along the to-be-examined body. With the ultrasonic probe supporting mechanism, the ultrasonic probe can suitably be positioned to measure a shape of a cartilage (to-be-examined part) of a knee joint, and the ultrasonic probe can suitably be moved along the to-be-examined body.